Tunable Charge Detectors for Semiconductor Quantum Circuits

TL;DR

This paper explores how tuning quantum point contacts into localized states enhances charge detection sensitivity in semiconductor quantum circuits, enabling faster and more precise measurements of quantum dots.

Contribution

It introduces a method to improve charge detector sensitivity by shaping quantum point contacts into localized states, demonstrated through experiments in the quantum Hall regime.

Findings

Enhanced charge detection sensitivity with localized states

Faster and well-resolved charge detection achieved

Improved control over electrostatic environment in quantum circuits

Abstract

Nanostructures defined in high-mobility two-dimensional electron systems offer a unique way of controlling the microscopic details of the investigated device. Quantum point contacts play a key role in these investigations, since they are not only a research topic themselves, but turn out to serve as convenient and powerful detectors for their electrostatic environment. We investigate how the sensitivity of charge detectors can be further improved by reducing screening, increasing the capacitive coupling between charge and detector and by tuning the quantum point contacts' confinement potential into the shape of a localized state. We demonstrate the benefits of utilizing a localized state by performing fast and well-resolved charge detection of a large quantum dot in the quantum Hall regime.